Conventional welding wire feed systems usually employ a pair of "pinch" rollers between which the welding wire is fed. While it is possible to provide the pinch rollers and motor for driving the same in a convenient position relative to a torch in in-shop welding applications, the wire feed control mechanism cannot always be easily accommodated in certain "in-place" welding operations. For example, in my co-pending patent application Ser. No. 211,359 filed Nov. 26, 1980 and entitled FULL FUNCTION IN-PLACE WELD HEAD there is described a very compact welding configuration for welding about pipes in awkward locations. The particular welding apparatus described utilizes a horseshoe-shaped rotating carriage for carrying the welding torch and certain other controls for movement of the torch head as well as the horseshoe carriage structure about the pipe to be welded. The configuration is designed to be very compact in the axial direction of the pipe to be welded so that where curved pipe portions are involved, the "in-place" welding feature can be realized.
In a welding structure of the foregoing type, it would be very difficult to accommodate the feed rollers and feed motor drive for the feed wire assembly on the welding head carriage. Rather, this structure is normally provided in a separate housing and an elongated guide tube utilized to feed the wire to the welding head carriage and welding torch. This tube normally ends in a ninety degree turn to properly position the wire. The feed rollers thus are essentially "pushing" the wire and because of the guide tube length and ninety degree bend, large friction can develop and complications can ensue in attempting to control the proper feed rate. It would be far more advantageous if the lengths of wire passing from the feed rollers could be kept as short as possible, so that essentially the feeding of the wire is effected by a "pulling" of wire from a remote supply reel into the torch.